Trifluoroacetic acid → 5-(3-methoxyphenyl)-3,4-dihydro-2H-pyrrole

Participants

Reaction Conditions

Reaction Steps

Add trifluoroacetic acid (49.8 mL, 670 mmol) to [4-(3-methoxy-phenyl)-4-oxo-butyl]-carbamic acid tert-butyl ester (22.21 g, 67 mmol) with ice/water cooling. After stirring at 0° C. for 3.5 h, adjust the reaction to pH 10 with 50% sodium hydroxide. Extract the reaction mixture with ether (5×100 mL), dry the combined organic layers over magnesium sulfate, filter, and concentrate under reduced pressure to obtain the crude product (15.43 g). Purify by flash chromatography [silica gel, 330 g, 0 to 30% gradient of (90:10:1 methylene chloride/methanol/concentrated ammonium hydroxide) in methylene chloride] to obtain the title compound (10.76 g, 88% for two steps). MS (APCI+): 176 [C11H13NO+H]+; 1H NMR (300 MHz, CDCl3): δ 7.46-7.45 (m, 1H), 7.37-7.27 (m, 2H), 6.99-6.95 (m, 1H), 4.09-4.03 (m, 2H), 3.84 (s, 3H), 2.96-2.89 (m, 2H), 2.08-1.97 (m, 2H).

Provenance & Evidence